I bought two pairs of these after someone on one of the car forums I frequent ranted about what a ridiculous value they are. I've been listening to them for about two weeks now, probably about 60 hours on them between a couple evenings worth of burn-in and listening to them on my iPod at work. I am fairly impressed by their performance for a measly $7.
As other people have mentioned, the stock tips are horrible. I had to cram them pretty far into my ears to get them to seal, and they were not only uncomfortable but also failed to stay put for more than 30 minutes at a time. These being my first foray into IEMs, I don't have a huge variety of tips to try out, but I have had good results using the small size tips that came with my ATH-CKM50s (yes, I have been reading up and purchased a few other bang-for-buck IEMs too
). Although they are a small tip size, they fit my medium-sized ears pretty well when crammed onto the large-ish nozzle of the 8320s. I can get a seal without having to stuff them into my ears as forcefully as I had to using the stock tips. They are reasonably comfortable and stay put until I intentionally remove them.
In stock form, the bass on these has decent extension but is lacking just a touch in weight IMO. I also noted that they were quite lively in the upper midrange. To address the bass I took the advice from another post in this thread and covered the little port near the nozzle with a ~4mm x 4mm piece of clear packing tape. That resulted in a tad too much bass, so I "tuned" them by putting a few small holes in the tape using a 27 ga needle. Regarding the upper midrange, it seems like the smaller hole in the CKM50 tips may have attenuated that a bit, though I haven't A/B'ed the tips to confirm that suspicion. Whether it was the change in tips, further burn-in, or simply me acclimating to their sonic signature, I don't find the upper midrange objectionable today like I did last week. I'm quite happy with these.